The present invention relates to overhead doors comprised of vertically spaced panels and, more particularly, to such doors having plastic cores and metal skins with improved but simple insulating features.
The use of panels formed of a core of lightweight insulating material clad with relatively thin metal skins, joined together by hinges to make strong, lightweight roll-up doors is virtually the standard design in the garage door industry.
Early designs used expanded foam, injected between front and rear metal skins, as the rigid, insulating core. However, problems with voids in such cores, along with the need for clamping jigs and sealing during the foaming operation have favored the use of preformed cores to which the metal skins may be rapidly affixed by adhesives.
With proper choice of core material and bonding agents, such panels can be fabricated in a fraction of the time and at a fraction of the cost of foamed-in-place panels, with little if any decrease in stength or durability. The metal skins of such panels can be embossed with wood grain or other patterns, and with simulated raised or recessed portions, moldings or other architectural details to match or enhance any design. Moreover, they may be painted or resin coated. They are much lighter than predecessor wood panels, and so can be countersprung with smaller and less costly springs and operated with smaller, less expensive motors in the door operators. Garage doors constructed in this way will not warp or rot as do wooden doors. In addition, such doors may provide excellent insulating properties which are so desirable for energy conservation.
Despite these many advantages, there are various problems which are inadequately addressed by various existing designs. Among these problems is the need to hold the inner and outer skins together to provide a clamping force between the skins on the surfaces of the core section they face. Among the means currently employed for this purpose are metal skins with complexly formed top and bottom ends, whose return edges are complementarily shaped to interlock with each other, thus holding the core material in compression while any interposed adhesive cures.
Another approach to solving this problem has been to use metal skins in which similarly formed top and bottom edges face each other like mirror images across an intervening preformed core, with the adjacent portions of the edges being held together by clips to provide contact pressure between the core and the metal skins while any interposed adhesive cures. Generally, such clips are quite small so they are usually made of metal to achieve the needed strength in the small cross section. To prevent thermal conduction between the front and rear metal skins, such clips are commonly faced with a conforming flexible resinous or ribbing material which provides a thermal break. Whether made of metal or any other material, such clips typically bridge either or both the top and bottom edges of each panel, and their presence tends to interfere with the generally essential weather and thermal seals.
Panels which are assembled into hinged sectional doors may also have along their top and bottom edges some form of elastomeric element which seals the joint between the panels when the door is closed. The simplest type of such weatherseal, regardless of its shape or composition, is a continuous member extending along the entire length.
Another problem with existing panel designs is the difficulty of adequately anchoring the hinges and other needed hardware in the panels, since neither the relatively soft core material nor the thin metal skin is sufficiently strong. Typical prior art solutions to this problem involve the use of thicker metal sections at hinge attachment points and at other stress locations. An alternative uses inserts of metal or wood to serve as load-bearing points. Both approaches tend to add cost and manufacturing time.
It is an object of the present invention to provide a novel garage door using metal clad door panels in which preformed core sections and stiles are readily assembled with metal skins of relatively simple configuration.
It is also an object to provide such doors in which the panels are strong, lightweight and relatively inexpensive.
A further object is to provide such doors which obviate the need for special inserts or structures as hardware attachment points.